The game is set in Shibuya, Tokyo. A girl named Hoshino Ichika, walks through the streets and sees an LCD screen displaying Hatsune Miku. Upon returning home, she discovers a song named "Untitled" on her smartphone. Out of curiously, Ichika plays the songs, only to get surrounded by a white light and arrive at an unknown place. Miku stands in front of Ichika, welcoming her to Sekai, and inviting her to sing together.